Don't be tense about tense

Prof Alta van der Merwe asked me to write up something about the use of tenses in a thesis, so that she could get her students to cite me.
I can resist anything except temptation, so, for the sake of citation, here goes, Alta!

Use the simple present tense for things that go on indefinitely. Use the past tense for things that have just happened, and the past perfect for things that had already been completed by the time the research took place.

Chapter 1 - Introduction
This thesis describes   research that was conducted to determine if there had been a significant improvement in the results of a given treatment.

So to explain more clearly.  If you are writing about the thesis itself, then you use the simple present.  Chapter One deals with the introduction, rationale and research method of the study. Chapter Two reports on the current literature. Chapter Three describes the methodology.  All in the present tense, because those chapters fulfil those functions right now, and always will.

Chapter 2 - Literature survey
The literature survey is written predominantly in the present tense.  Smith and Jones say: "We don't know what we are doing but we publish it anyway" (2014 p. 67).  Note that Smith and Jones are two authors, so they say.  But the article by Smith and Jones says, because it is just one article.  If, however, you are telling the story of Smith and Jones and their research, then it is in the past tense. Smith and Jones conducted research in the 1990s, and found numerous instances of people publishing in fields that they know nothing about. As their article puts it (present tense) "People publish for the sake of seeing their name in print, rather than to contribute to knowledge" (Smith and Jones, 1990 p. 27).

Chapter 3 - Research methods
Here you use mainly the past tense.  You are describing what you did.  If you have to follow up on things that had already been done, then you use the past perfect, and if you have to cite and author to substantiate what you did, then you use the present tense.
Questionnaires were distributed among the participants who had already viewed the movie and they were asked to complete a four-point Likert scale,  Johnson (2013) suggests that a Likert scale should have an even number of points to prevent participants from taking a mid-point position.

Chapter 4 - Findings
All in the past tense.  It is what you found.  Even if you found things that will hold true indefinitely, it still remains in the past, because that is when you found it.  Yesterday I found that the sky was blue. The fact that it is blue today, and will probably be so tomorrow is irrelevant.

Chapter 5 - Conclusions and recommendations
Conclusions are written in the present tense.  The conclusions are your contribution to the body of knowledge.  It was found that some people did one thing and other people did another. The conclusion is that different people do different things.
Recommendations are written in the imperative.  More research should be conducted to determine the circumstances under which people do what they do.

So that's it. No need to be tense about tense.  Just tell it as it happens.

Image with permission by Dr Raa Khimi who is also the author of the book   Science & Engineering Research Writing Template

  https://www.amazon.com/Science-Engineering-Research-Writing-Template/dp/967148560X